The present invention relates to a vinyl chloride resin, a method of producing it, and molded products of the same.
Vinyl chloride resin is outstanding in mechanical strength, weathering resistance and chemical resistance and has been used in many applications. However, for use in certain applications such as architectural materials including sidings, window frames and sashes or rigid products including pipes and joints, the species of vinyl chloride resin heretofore in use are deficient in impact resistance, for instance, and, therefore, several techniques for overcoming the drawback have so far been proposed.
Japanese Kokai Publication Sho-60-255813 discloses a technology of producing a vinyl chloride resin with improved impact resistance, weathering resistance and elastic modulus in flexure which comprises graft-copolymerizing vinyl chloride with an acrylic copolymer comprising an acrylic monomer which gives a homopolymer having a glass transition point of not over xe2x88x9210xc2x0 C. and a polyfunctional monomer.
Japanese Kokai Publication Hei-8-225622 discloses a vinyl chloride resin comprising a particulate acrylic copolymer latex and having a core-shell structure as graft-copolymerized with vinyl chloride.
Japanese Kokai Publication Hei-9-110945 discloses a vinyl chloride resin obtainable by graft-copolymerizing a copolymer composed of a radical-polymerizable monomer which gives a homopolymer having a glass transition point of not higher than xe2x88x9260xc2x0 C. and a polyfunctional monomer with a monomeric mixture comprising an acrylic monomer which gives a homopolymer having a glass transition point of not below xe2x88x9255xc2x0 C. and a polyfunctional monomer and further graft-copolymerizing the resulting graft-copolymer with vinyl chloride.
These techniques have invariably contributed to improved impact resistance of vinyl chloride resin but the product resins are invariably low in glass transition temperature and contain an acrylic latex which is a tacky rubber component liable to adhere and accumulate on the metal mold in an extrusion process to give rise to thin spots and streaks on the product surface, thus detracting seriously from the aesthetic quality of the product. Particularly in counter extrusion, the problem of poor product appearance is frequently encountered. Therefore, there is an industrial need for vinyl chloride resin which is conducive to steady production of moldings of good surface condition even over many hours of continuous production.
The object of the present invention is to overcome the above disadvantages of the prior art and provide a vinyl chloride resin conducive to the production of moldings having a high impact resistance and a satisfactory surface condition over many hours of continuous production with good reproducibility, a method of producing such a vinyl chloride resin, and a molded product as obtainable therefrom.
The first aspect of the present invention is concerned with a vinyl chloride resin as obtainable by graft-copolymerizing an acrylic copolymer (a) having a mean particle diameter of 60 to 250 nm with a vinyl monomer (b) predominantly composed of vinyl chloride,
said acrylic copolymer (a) being obtainable by graft-copolymerizing 40 to 90 weight % of a copolymer (axe2x88x921) with 10 to 60 weight % of a mixture monomer (axe2x88x922),
said copolymer (axe2x88x921) being composed of 100 weight parts of a radical-polymerizable monomer which gives a homopolymer having a glass transition point of not lower than xe2x88x92140xc2x0 C. but lower than xe2x88x9260xc2x0 C. and 0.1 to 1 weight part of a polyfunctional monomer, and
said mixture monomer (axe2x88x922) comprising 100 weight parts of a radical-polymerizable monomer predominantly comprised of a (meth)acrylate which gives a homopolymer having a glass transition point of not lower than xe2x88x9255xc2x0 C. but lower than xe2x88x9210xc2x0 C. and 1.5 to 10 weight parts of a polyfunctional monomer.
The second aspect of the present invention is concerned with a vinyl chloride resin comprising
a matrix resin predominantly composed of polyvinyl chloride and, as dispersed therein, a particulate acrylic copolymer (a) having a glass transition point of not lower than xe2x88x92140xc2x0 C. but lower than xe2x88x9220xc2x0 C., a gel fraction of 50 to 100 weight % and a mean particle diameter of 60 to 250 nm,
the graft ratio of vinyl chloride to said acrylic copolymer (a) being 0.1 to 5 weight %.
The third aspect of the present invention is directed to a method of producing a vinyl chloride resin comprising
reacting 100 weight parts of a radical-polymerizable monomer with 0.1 to 1 weight part of a polyfunctional monomer to give a copolymer (axe2x88x921), where said radical-polymerizable monomer gives a homopolymer having a glass transition point of not lower than xe2x88x92140xc2x0 C. but lower than xe2x88x9260xc2x0 C.,
graft-copolymerizing 40 to 90 weight % of said copolymer (axe2x88x921) with 10 to 60 weight % of a mixture monomer (axe2x88x922) to give an acrylic copolymer (a) having a mean particle diameter of 60 to 250 nm, where said mixture monomer (axe2x88x922) comprises 100 weight parts of a radical-polymerizable monomer predominantly comprised of a (meth) acrylate which gives a homopolymer having a glass transition point of not lower than xe2x88x9255xc2x0 C. but lower than xe2x88x9210xc2x0 C. and 1.5 to 10 weight parts of a polyfunctional monomer
and graft-copolymerizing said acrylic copolymer (a) with a vinyl monomer (b) predominantly comprised of vinyl chloride.
The fourth aspect of the present invention is concerned with a rigid vinyl chloride resin molded product
which comprises a matrix resin predominantly composed of polyvinyl chloride and, as dispersed therein, a particulate acrylic copolymer (a) having a glass transition point of not lower than xe2x88x92140xc2x0 C. but lower than xe2x88x9220xc2x0 C., a gel fraction of 50 to 100 weight %, and a mean particle diameter of 60 to 250 nm,
the graft ratio of vinyl chloride to said acrylic copolymer (a) being 0.1 to 5 weight %.
The fifth aspect of the present invention is concerned with a pipe, as an example of the rigid vinyl chloride resin molded product according to said fourth aspect,
which has a Charpy impact strength value of not less than 100 kgfxc2x7cm/cm2 and a tensile strength value of not less than 460 kgf/cm2.
The sixth aspect of the present invention is concerned with a deformed extrusion, as an example of the rigid vinyl chloride resin molded product according to said fourth aspect,
which has a Charpy impact strength value of not less than 10 kgfxc2x7cm/cm2and a tensile strength value of not less than 400 kgf/cm2.
The seventh aspect of the present invention is concerned with a pipe of the vinyl chloride resin according to said first aspect or second aspect of the invention,
which has a Charpy impact strength value of not less than 100 kgfxc2x7cm/cm2 and a tensile strength value of not less than 460 kgf/cm2.
The eighth aspect of the present invention is concerned with a deformed extrusion of the vinyl chloride resin according to said first aspect or second aspect of the invention,
which has a Charpy impact strength value of not less than 10 kgfxc2x7cm/cm2 and a tensile strength value of not less than 400 kgf/cm2.
The ninth aspect of the present invention is concerned with a plastic sash comprising the rigid vinyl chloride resin molded product according to said sixth aspect of the invention or said eighth aspect of the invention or the deformed extrusion according to said eighth aspect of the invention.